A wireless charging system includes a wireless power receiver and a wireless power transmitter. The wireless power transmitter is coupled to an input power source. When the wireless power receiver is within close proximity to the wireless power transmitter, the wireless power transmitter and the wireless power receiver are magnetically coupled thereby causing energy to be transferred from the wireless power transmitter to the wireless power receiver. The wireless power receiver uses the received energy to power an external load, such as to power a mobile device or to charge a battery. The amount of the energy that is transferred is typically controlled by wireless communication between the wireless power transmitter and the wireless power receiver. The wireless power transmitter typically includes power supply circuitry that receives a supply voltage from the input power source. A more robust solution is desired.